High-end precision casting dedicated silica sol
#Application
·2025-08-21 17:08:51
gao
High-end precision casting-specific silica sol is a high-performance binder used in the precision casting field, usually composed of nano-scale silica particles dispersed in water to form a colloidal solution. Here is its detailed introduction:
- Characteristics
- Small particle size and uniform distribution: For instance, the particle size of S-830 silica sol is between 8 and 10nm. The relatively small particle size endows it with excellent filling properties, effectively filling the tiny pores in the mold, making the shell more compact, and thus ensuring high surface finish and precise dimensions of the casting.
- Strong adhesiveness: Silica sol has high adhesiveness. For instance, S-830 silica sol can firmly bond refractory materials, forming high-strength shells that can withstand high temperatures and the erosion of molten metals during the casting process.
- Good high-temperature stability: During high-temperature calcination, silica sol forms stable silicon-oxygen bonds, capable of withstanding temperatures of 1500-1600℃, which enhances the strength of the mold shell and reduces the risk of cracking.
- Low impurity content: Compared with traditional sodium silicate binders, silica sol contains almost no harmful ions such as Na⁺ and K⁺, which can reduce surface defects of castings, improve the quality and yield of castings.
- Good fluidity and permeability: The low viscosity property enables it to penetrate well into the tiny pores of the mold, ensuring uniform coating and facilitating the formation of high-quality shells.
- Its role in high-end precision casting
- Improving the surface quality of castings: As a surface coating, the nanoscale particles of silica sol can effectively fill the tiny pores on the surface of wax molds, making the shell surface smoother and thereby reducing the surface roughness of castings. The Ra can reach below 3.2μm, reducing the subsequent machining volume and saving costs.
- Enhanced shell strength: Silica sol is used to bond refractory materials, forming multi-layer shells, providing stable support for the casting process, reducing the risk of shell deformation and cracking at high temperatures, and is suitable for casting difficult-to-machine materials such as stainless steel and high-temperature alloys.
- Improving production efficiency: For instance, using S-1430 silica sol as the back layer material can reduce the interlayer drying time, accelerate the production pace, and at the same time, it is conducive to demolding, reduces the time and cost input for sand cleaning, and enhances the overall production efficiency.
- Types and application examples
- Surface layer silica sol: Represented by S-830 silica sol, it is an alkaline small-particle silica sol with a pH value typically ranging from 9 to 10. It features a large specific surface area, high high-temperature strength, and low shrinkage. It is mainly used for the surface layer in precision casting, which can make the dimensions of the castings accurate and the surface layer smooth.
- Back layer silica sol: such as S-1430 silica sol, with an average particle size of 10-16nm and a SiO₂ content of 29-31%, it features high strength and heat resistance, providing stable support for shell molds, reducing the risk of high-temperature deformation and cracking. As a back layer material, it can shorten the interlayer drying time and enhance production efficiency.
